Carbon film electrodes for super capacitor applications

Abstract

A microporous carbon film for use as electrodes in energy strorage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm2 and 1 g/cm2 and a gravimetric capacitance of about between 120 F/g and 315 F/g.

I claim: 
     
       1. A microporous carbon film for use as electrodes in energy storage devices made by the process comprising the steps of: a) heating a polymer film consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in air or in an inert atmosphere to a first heating temperature of about 160° C. and maintaining said first heating temperature for at least 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, said polymer film disposed between graphite or ceramic plates wherein the graphite or ceramic plates are separated by spacers, said spacers having a height about equal to twice the thickness of said polymer film;   b) heating the stabilized vinylidene chloride/vinyl chloride polymer film, in an inert atmosphere, from said first heating temperature to a second heating temperature of about between 740° C. to 750° C., said step of heating to said second heating temperature further comprising increasing said temperature at a uniform rate of about 5° C. per minute and maintaining said second heating temperature for about one hour to form a carbon film; and   c) activating said carbon film by introducing an oxidizing gas into, and substantially displacing, said inert atmosphere while maintaining said film temperature above about 750° C. to about 850° C. for between 1 and 6 hours thereby providing said microporous carbon film having a gravimetric electrical capacitance of between 120 F/g and 315 F/g.   
     
     
       2. The carbon film by the process of claim 1 wherein the first heating step further comprises the steps of: a) heating said polymer film material from room temperature to a temperature of about 100° C. at a rate of about between 2° C.-3° C. per minute and holding said polymer film material at about 100° C. for about one hour;   b) increasing said temperature to about 130° C. and holding said polymer film material at 130° C. for between 2 to 3 hours;   c) increasing said temperature to about 150° C. and holding the polymer film material at 150° C. for about 2 hours; and   d) increasing said temperature to about 160° C. and holding the polymer film material at 160° C. for between 14 to 28 hours.   
     
     
       3. The carbons film by the process of claim 1 including the step of soaking said polymer film in a liquid selected from the group consisting of water, methanol, and acetone, said step of soaking preceding the first heating step. 
     
     
       4. The carbon film by the process of claim 1 wherein the oxidizing atmosphere is CO 2 . 
     
     
       5. A microporous carbon film for use as electrodes in energy storage devices made by the process comprising the steps of: heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and   activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm 2  and 1 g/cm 2  and a gravimetric capacitance of about between 120 F/g and 315 F/g.